1. Field of the Invention
This invention relates to a display device for modulating a light beam to display a picture, and more particularly to a transmissive display device using a micro light modulator that is capable of improving a light efficiency.
2. Description of the Related Art
Nowadays, there has been actively made a study of various flat panel display devices expected to be next generation display devices. Such flat panel display devices include a liquid crystal display (LCD) and a plasma display panel (PDP), etc. available in the market. The LCD has disadvantages in that it has a narrow view angle and a slow response speed and that its fabrication process is complicated because thin film transistors (TFT""s) as switching devices and electrodes, etc. are formed by a semiconductor fabrication process. On the other hand, the PDP has an advantage in that its fabrication process is simple to provide a large-dimension screen. However, the PDP has a disadvantage in that it has low discharge and luminescence efficiencies.
Accordingly, there has been conducted a development of a novel display device capable of overcoming such problems in the flat panel devices. Recently, there has been suggested a transmissive display device that forms a micro light modulator for each pixel using a micro electro-mechanical system (MEMS) as an ultra-fine processing technique so as to display a picture.
FIG. 1A and FIG. 1B are a schematic section view and a schematic side view showing a structure of a conventional transmissive display device using a micro light modulator, respectively. Referring to FIGS. 1A and 1B, the conventional transmissive display device includes a plurality of stationary members 13 provided on a transparent substrate 11 in a line with and at a desired distance from each other in a stripe shape, and a plurality of movable members 15 taking a bridge shape to be space from the stationary members 13 and have each side overlapped with the stationary members 13.
The movable members 15 with a bridge shape has each end secured to the transparent substrate 11 and has a center portion floated, by a desired distance, from the transparent substrate 13 to be spaced from the stationary members. The stationary members 13 are formed from a multi-layer thin film consisting of a conductive material for an electrode and an insulating material for an insulating layer, etc. On the other hand, the movable members 15 are formed from a good elastic material and a multi-layer thin film consisting of a conductive material for an electrode and an insulating material for an insulating layer, etc. The stationary members 13 and the movable members 15 have opaque surfaces.
The movable members 15 are formed by depositing a sacrifice layer (not shown) on the transparent substrate 11 provided with the stationary members 13, and then depositing a good elastic material, a conductive material for an electrode and an insulating material for an insulating layer used to form the movable members 15 on the sacrifice layer in such a manner to be contacted with the transparent substrate 11 and patterning the same, and thereafter removing the sacrifice layer.
In the transmissive display device having the configuration as mentioned above, the stationary members 13 and the movable members 15 are controlled by an electrical signal to indicate a display state and a non-display state of a screen. More specifically, the stationary members 13 and the movable members 15 are connected or disconnected by a static electricity force exerting mutually in accordance with an electrical signal applied to each electrode to open or close a light path, thereby indicating a screen state.
FIG. 2A and FIG. 2B are section views of the conventional transmissive display device using a micro light modulator upon driving thereof. Referring to FIG. 2A, there is shown a non-display state of the transmissive display device in which, if a switch S is turned on, a desired level of voltage is applied to each electrode of the stationary members 13 and the movable members 15. At this time, an attractive force caused by a static electricity is exerted between the stationary members 13 and the movable members 15 to move the movable members 15 into the stationary members 13. This contacts each overlapped portion between the stationary members 13 and the movable members 15. Accordingly, an incident light from a rear light source (not shown) installed at the rear side of the transparent substrate 11 is reflected by the stationary members 13 and the movable members 15 such that it fails to transmit the display device to be shut off.
Referring now to FIG. 2B, there is shown a display state of the transmissive display device in which, if the switch S is turned off, no voltage is applied to the stationary members 13 and the movable members 15. At this time, since the movable members 15 is returned to its primary state due to its elastic force to be disconnected with the stationary members 13, gaps are defined between the stationary members 13 and the movable members 15. This forms a light path between the stationary members 13 and the movable members 15. An incident light inputted, via that light path, from the rear light source (not shown) is transmitted into a display screen (not shown) to display a picture or an image.
As described above, the conventional transmissive display device using a micro light modulator requires a sacrifice layer to keep a distance between the stationary member and the movable member constantly. However, since it is not easy to form the sacrifice layer into a constant thickness, it becomes difficult to keep a distance between the stationary member and the movable member constantly.
Accordingly, it is an object of the present invention to provide a transmissive display device using a micro light modulator that is capable of easily controlling a distance between each stationary member and each movable member so as to keep said distance constantly.
In order to achieve these and other objects of the invention, a transmissive display device using a micro light modulator according to the present invention includes first and second transparent substrates, each of which has first and second surfaces; a plurality of stationary members provided on the first surface of the first transparent substrate 21 in a line with and at a desired distance from each other in a stripe shape; a plurality of movable members opposed to portions at which the stationary members are not provided on the first transparent substrate and taking a bridge shape to have each end secured to onto the first surface of the second transparent substrate and a center portion floated by a desired distance; and spacers provided at the edges of the display device in such a manner that the first surface of the first transparent substrate is opposed to the first surface of the second transparent, thereby constantly keeping a distance between each stationary member and each movable member.